The plasma membrane of granulosa-lutein cells with its myriad of different receptors and constitutive enzymes is thought to be primarily responsible for controlling the rate of metabolic activity within the cell. Activation of cell, like the membrane itself, is complex and involves many factors including hormone receptor interactions, production of cyclic nucleotides, calcium transport, ionic and pH shifts and the influx of metabolites. The problem, however, is that cellular responsiveness varies with both the time of the cycle or previous exposure to tropic hormones. Factors thought to regulate this variable responsiveness involve either changes in the molecular configuration of membrane constituents or selective insertion and removal of secifc macromolecules, or both. To understand how the functions of the ovary are controlled we must know much more about these dynamic aspects of plasma membrane function. The studies outlined in this proposal are designed to analyze the synthesis and flow of plasma membrane components through mature granulosa lutein cells in pigs. Our specific objectives will be to a) determine where new gonadotropin receptors are synthesized and how they are inserted in the plasma membrane b) analyze the specificity involved in receptor internalization and degradation, c) identify the role of microtubules and microfilaments in the flow of plasma membrane components both within the cytoplasm and on the cell surface and d) initiate studies on receptor synthesis, insertion internalization and degradation in marmosets. The pig C.L. is the best model available for these studies because we must have large quantities of tissue for studies involving density gradient centrifugation of subcellular components (slaughter house 150 ovaries per day) and yet have an animal we can experimentally and surgically manipulate under laboratory conditions (miniature swine). In addition, most required culture procedures have been worked out and the cultured C.L. cells and slices have responded well to porcine LH and hCG in vitro. The work is important because it should lead to a greatly improved understanding of mechanisms controlling ovarian function.